1. Wrong: Lee takes a passive role, I think, in her own life.
Better: Lee takes a passive role in her own life. [Then, support with evidence from Prep.]
Explanation: Of course the writer of this essay thinks that Lee takes a passive role in her own life because she's writing that idea in her essay. Instead of weakening the claim with I think, she should strengthen it with textual proof and analysis.
2. Wrong: Even though Holden lies all the time, you can see that Holden has a lot of problems with people he thinks lie to him.
Better: Even though Holden lies all the time, he has a lot of problems with people he thinks lie to him.
Explanation: The you can see doesn't add anything to the claim.
3. Wrong: In my opinion, several of the characters make bad choices.
Better: Several of the characters make bad choices. [Then, support with evidence.]
Explanation: Every essay should show the writer's opinion, substantiated by evidence from the text.